OBD-II trouble code
U0341: Software Incompatibility With Hybrid/EV Battery Interface Control Module H
On a hybrid or electric vehicle with a multi-segment high-voltage battery pack, a module has detected that battery interface control module H is running software or a calibration that doesn't match the rest of the vehicle's modules. It's a programming mismatch, not a wiring fault, usually following battery service, module replacement, or a reflash.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $150 – $700
- DIY difficulty
- Shop recommended
What does U0341 mean?
U0341 is the eighth code in the lettered battery-interface software-incompatibility series, covering interface control module H. It's found on the same category of vehicle as U0340 and its predecessors: hybrid and electric platforms with high-voltage packs split into enough physical segments or contactor groups that the manufacturer designed in a dedicated interface controller for each one. Module H manages contactor engagement, pre-charge sequencing, and interlock monitoring for its segment, and reports that status to the battery control module and pack sensor module, the same as the other lettered modules. U0341 sets when another module on the network determines that interface control module H's software or calibration version is outside the version-matched set the rest of the vehicle's modules expect — the module is communicating, but its programming doesn't fit.
The cause is, again, almost always tied to recent service on the high-voltage battery system: a replacement interface module or battery segment installed without correct VIN-specific programming, a software update that reached most of the battery system's modules but not module H, or a reflash of module H using an incorrect calibration file or one that didn't complete properly. Since the problem is in the module's stored software rather than its wiring, standard electrical checks won't be productive — reprogramming module H to the vehicle's current approved calibration is what resolves it.
Because module H, like its lettered siblings, has direct authority over contactor behavior for its portion of the pack, a software mismatch here produces the same conservative vehicle response: restricted power output, that segment staying offline, or the vehicle not reaching a full 'Ready' state rather than operating on unverified logic. This is why U0341 is rated medium severity even though the vehicle typically remains driveable to some degree. A drop in available power, a longer-than-normal power-up, or additional high-voltage codes stored with U0341 should be addressed promptly by a shop equipped for that vehicle's high-voltage system.
Common causes
- Battery interface control module H or its associated pack segment installed without correct VIN-specific programming
- A used or reconditioned interface module installed without being re-learned to this vehicle
- A battery-system software update that reached other modules but skipped module H
- An interrupted or incomplete reflash of interface control module H
- Reprogramming performed with the wrong calibration file or wrong segment configuration selected
- Mismatched hardware/software part numbers following high-voltage battery service or segment replacement
Symptoms
- Warning light and a stored U0341 (often alongside other lettered interface-module codes)
- Reduced available power or the vehicle failing to reach a full 'Ready'/drive state
- A specific battery segment or contactor group failing to come online
- High-voltage system fault messages on the dash
- Condition typically appears right after high-voltage battery service, a module replacement, or a reflash
Diagnostic steps
- 1.Confirm recent service history — U0341 almost always follows high-voltage battery work, an interface module replacement, or a software update; identify exactly what was serviced.
- 2.Using a scan tool rated for hybrid/EV high-voltage systems, read battery interface control module H's software/calibration part number and compare it against the manufacturer's approved set for the VIN.
- 3.Check for companion codes on other lettered interface modules to confirm module H specifically is the mismatched unit.
- 4.Verify the module or segment was programmed with correct VIN-specific data, not generic or wrong-segment software.
- 5.Follow all high-voltage safety procedures (insulated tools, proper lockout/disconnect) before any physical inspection.
- 6.Reprogram/reflash battery interface control module H to the matching, up-to-date calibration using a manufacturer-approved tool.
- 7.Clear codes and confirm U0341 does not return and the vehicle powers up and drives normally through several key cycles.
Repair cost
$150 – $700
This is primarily a programming fix. Reprogramming the interface control module typically runs $150-$400, and up to $700 when dealer-only high-voltage calibrations, special tooling, or a broader battery-pack service are involved. If an incorrect segment or module was physically installed, correcting that hardware is the larger expense; U0341 itself is usually resolved by correct reprogramming. Costs run higher than typical U03xx codes due to the specialized high-voltage equipment and training required.
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DIY vs shop
Leave this one to a qualified shop. It typically involves emissions-critical components, refrigerant handling, or other work that requires manufacturer-grade tooling, training, or certification. DIY attempts often produce a more expensive problem than the original code.